where \(t_{k}\)  denotes the exposure time of the \(k\) -th image \(I_{k}\) . \(\gamma \)  is a
gamma correction parameter, which is set to 2.2. Following [1]}, we concatenate \(I_{k}\)  and \(H_{k}\)  along the channel dimension to obtain a 6-channel input \(X_{k}=\left\lbrace I_{k}, H_{k}, i=1,2\right\rbrace \) .
Therefore, the process of obtaining HDR images can be expressed as:
\(H=\mathbf {M}\left(X_{1}, X_{2}; \theta \right)\) 
